Is humanity still evolving?

April 15, 2007 12:58 PM

Is health care technology impeding our species' ability to evolve and adapt?

I've heard debates that the human species has stopped evolving because our evolving health care technology has stopped the process of natural selection. This would, in theory, make humanity less able to adapt to change (ie an ice age), and weaken our gene pool.
Another idea that I have heard expressed on this topic is that genetic engineering (a future possibility) will reverse this stagnation.
I would like to find out more information on this topic so any suggestions on papers/websites to read, or any opinions would be great. I've already read the thread at http://ask.metafilter.com/40631/Swim-Walk-Fly.

Thanks!

posted by azriel2257 to science & nature (32 comments total)

Health care technology IS our ability to evolve and adapt!
posted by Cosine at 1:07 PM on April 15, 2007 [2 favorites]

This argument sounds like eugenics dressed up in pretty clothes to me.
posted by Happy Dave at 1:16 PM on April 15, 2007

Also, it's startlingly Western-centric. Fully two thirds of the world's population have shockingly basic healthcare - have they 'stopped evolving' too?
posted by Happy Dave at 1:17 PM on April 15, 2007 [1 favorite]

I've had similar thoughts, and its not eugenics, just biology. I specifically think of things that typical humans select for that we now mask or augment. I am not sure why we select for things, such as certain facial hair patterns or what not, but what if we select for those things based on an underlying biological purpose that we are now subterving!
posted by stormygrey at 1:27 PM on April 15, 2007

Well... (Actually I found that while looking for this, about the disappearing y chromosome.)
posted by kimota at 1:30 PM on April 15, 2007

Cosine wins! And not just for being first.

Natural selection in the genetic sense is much too slow for us today. It explains how we came about, but isn't much of a vision for the future. Humans probably first discovered fire as a result of a random lightning strike, but it doesn't have much to do with where we took it.

For us, natural selection and evolution occur in the realm of reason and ideas, which is both more humane and faster to the nth degree.
posted by Bokononist at 1:31 PM on April 15, 2007

(Damn, number-based links versus text-based links threw me off.)
posted by kimota at 1:32 PM on April 15, 2007

Cosine nails it. Humans are a tool using species, there's no going back. Medicine is our way of adapting and surviving.

Secondly, its not just modern healthcare. Anything that someone could arguably live through. So if an early human tribe washed the germs off their food, that would make them "weaker" in the context of your question. If those germs killed 20% of the tribe then there's a very slim chance it will allow someone with a great immunue system to maybe have more kids and possibly spread those genes more than if they didnt wash their food. This practice culminates into what we call germ theory and good sanity/hygenic practices.
posted by damn dirty ape at 1:37 PM on April 15, 2007

As far as I understand it, there's no way to actually stop evolution, unless we come up with some completely new way of having children.

Even if we designed our children from scratch, the influence our own genes have on our decisions would make it a form of evolution.

One could argue that there's a difference between natural evolution and artificial, but I'd agree with Cosine in that our artificial technologies are part of how we evolve.
posted by lucidium at 1:55 PM on April 15, 2007

Don't think so highly of humanity. We have no power to stop evolution.

Evolution is solely concerned with the ability of a species to survive to reproductive age and reproduce. If medical technology helps that to occur in more individuals, it is technically an asset to our evolution, an adaptation that increases our fitness, evolutionarily speaking.

Also, consider the idea that with a greater diversity of individuals surviving and reproducing, there is actually a wider gene pool to draw from when and if the need for adaptation presents itself. Perhaps individuals with fibromyalgia or multiple sclerosis or Crohn's disease will one day turn out to be immune, by virtue of their affliction, to a pandemic that sweeps the world and wipes out much of humanity. That's an extreme, highly unlikely example, obviously, but it's the concept that's important here. Evolution continues whether we want it to or not.

As a final note, much of our modern healthcare technology is designed to increase the lifespan of people who have already passed reproductive age, rather than increasing the number of people who survive to see it. Once you've passed the "able to reproduce or reproducing" stage, you're completely irrelevant to evolution.
posted by po at 2:07 PM on April 15, 2007 [1 favorite]

As Happy Dave points out, most people today don't have access to health care, so at the present time it won't have much influence on humanity's evolution either way.

I don't think it's productive to cry "eugenics" every time someone asks a question of this nature. It's kind of an indirect Godwin.
posted by zixyer at 2:24 PM on April 15, 2007

Evolution is a LONG process, and the span of human history is VERY, VERY short.

Sixty Men from Ur:

Arthur M. Schlesinger, Jr., one the United States' great historians, is less than two lifetimes removed from a world where the United States did not exist. Through Mr. Schlesinger, you're no more than three away yourself. That's how short the history of our nation really is.

Not impressed? It's only two more life spans to William Shakespeare. Two more beyond that, and the only Europeans to see America are those who sailed from Greenland. You're ten lifetimes from the occupation of Damietta during the fifth crusade. Twenty from the founding of Great Zimbabwe and the Visigoth sack of Rome. Make it forty, and Theseus, king of Athens, is held captive on Crete by King Minos, the Olmecs are building the first cities in Mexico, and the New Kingdom collapses in Egypt.

Undoubtedly there's been some minor evolutionary pressure in that time, but for the most part, we haven't had time to substantially evolve within the entire scope of recorded history much less in the very brief time in which there has been modern medicine.
posted by willnot at 2:24 PM on April 15, 2007 [3 favorites]

think about it in reverse, the last 100 years of medicine have had the type of impact on humanity that natural selection would have probably taken thousands of years. time to read some cyberpunk!
posted by yeahyeahyeahwhoo at 2:30 PM on April 15, 2007

Sickle cell anemia is an example of what po said. Having both genes makes you pretty ill; but it's far more common to only carry one, which modifies your blood just enough that you're pretty well protected against malaria.
posted by spaceman_spiff at 2:31 PM on April 15, 2007

Humans have had some interesting level of technology for, what, a thousand years? Two?

Medicine that actually works for ... a few decades?

Evolution works on a completely different timescale. Check back in a hundred thousand years, and we'll see if humans are still evolving.

Don't think you can predict the behavior of humans over the next hundred thousand years based on what people have been up to in the last century - or millennium.
posted by dmd at 2:58 PM on April 15, 2007 [1 favorite]

And what willnot said.
posted by dmd at 2:59 PM on April 15, 2007

Humans have been evolving in tandem with their cultural adaptations since before they were human. For instance, we started cooking our food before we were homo sapiens sapiens, which allowed for a wider and more easily chewable range of nutrients. This increase in nutrient availability resulted in a decrease in jaw and tooth size, which in turn meant smaller jaw muscles which in turn allowed for larger skulls, and in particular allowed space for the frontal lobes to develop. So, cooking food is closely linked to the evolution of our brains, and arguably did not make us "weak" (in fact, it increased the gene pool considerably by allowing more individuals to survive). I could make a similar argument for a link between clothing and the spread of humanity over the globe.

Cultural adaptation alleviates certain environmental pressures, which changes the course of evolution, but it does not stop evolution, nor does it make us "weaker." The concept of natural selection is environmentally specific. Cultural interventions like medical technology change the environment in which we live. However, we continue to adapt to the new environment, and we have been historically very good at maintaining the cultural technologies that have become necessary to our survival (like cooked food and clothing).
posted by carmen at 3:05 PM on April 15, 2007

Now cloning, there's a threat to evolution...
posted by smackfu at 3:10 PM on April 15, 2007

There's reason to believe that the significant increase in the prevalence of the gene for cystic fibrosis in people of European descent is a result of the Black Death. It's similar in some ways to the Sickle Cell gene.

If you're heterozygous with the sickle gene, you are strongly resistant to malaria. And if you're heterozygous with the cystic fibrosis gene, it seems that you have a much better chance of surviving severe diarrheal diseases. What with maybe half of Europe dying over the course of 4 years, there was a very tiny incremental change in the genome of the people living there.

That's what evolution is like. Vast numbers of premature deaths pay for imperceptibly small evolutionary changes. For us who are alive, the price is too high. That's why we've developed medical science.
posted by Steven C. Den Beste at 3:13 PM on April 15, 2007

I almost made a small contribution to the evolutionary cause when I was about 4. Fortunately for me, modern medicine was around to save my life.
posted by Steven C. Den Beste at 3:16 PM on April 15, 2007

You can't stop evolution, you can merely alter the natural selection criteria.
posted by fvw at 3:31 PM on April 15, 2007

To cite one simple example, the ubiquity of c-section births will likely lead to an increase in average head size. Neonatal head size is no longer the life-limiting factor that it once was.

More broadly, humanity's nascent ability to modify its own genome will likely lead to a very rapid increase in the rate of evolutionary change of our species. Natural selection will still take place, but rather than operating on random mutations, it will operate on mutations targeted by bioengineers. I'd bet that within two or three hundred years, the human species will have evolved more than it has over the last thirty thousand years.

On the other hand, if you're looking for racist drivel you could argue that a broad and robust social safety net allows the least fit to survive and breed. Combine this with the fact that the least educated tend to reproduce in the largest numbers and you have an overall devolution of the species.

Combine the two and you have a bifurcation of the species into an engineer super-race, and a dumbed-down servant class.
posted by alms at 3:44 PM on April 15, 2007 [1 favorite]

alms, I don't think you can de-evolve. Humans aren't going to grow gills (for example) unless a gill-requiring environment engulfs the earth (maybe not even then).

Also, it's the best fit for the environment. In the jungle, I think the best fit for that environment is the crocodile not the pretty but useless hummingbird. (Of course, I'm not saying a hummingbird is useless . . .)

"The Time Machine" is fiction not science.

As a counter to silly people, you might also consider that by focusing on "purity" of any race they're dooming themselves to extinction because of a lack of diversity. Or what po said.
posted by who squared at 6:45 PM on April 15, 2007

Actually, what you've heard is pretty close to true, but only in a very narrow sense. In Western society especially, health care has reduced the environmental selection on our genes - well at least certain ones. Myopia isn't really a dangerous condition to have nowadays, so the genes that predispose somebody to it are not being selected against as much as they would've been in hunter-gatherer societies. But as carmen and fvw pointed out, natural selection is linked to the environment, and as we continue to change our environment, we don't know what genes are being selected for and against. So we can't really say that natural selection isn't occurring, we just know that our health care system is good enough to allow individuals to survive today when they mightn't have survived in the past.

However, the health care system isn't weakening our gene pool, it's strengthening it. By maintaining our genetic diversity. Because what is considered weak/undesirable today might be an advantage tomorrow. Steven C. Den Beste cited the classic example with sickle cell anemia and malaria - which is spouted out to all genetics students and helps us realise that the interplay between our genes and our environment is a complex one, and that some genes are capable of providing a selective advantage or disadvantage, depending on the environment.

We're an incredibly diverse species. There are people on this earth who are resistant to HIV, and others who have six fingers. Neither of these traits are particularly commonplace, but given the right selective pressure, they could be. For the race, it's could to have them around.
posted by kisch mokusch at 8:01 PM on April 15, 2007

Oh, and I'll just add a note about evolution. In the strictest sense, evolution is change over time. Now brand new additions to our gene pool, yes - that seems to take a long time (or not, who knows?). But changes due to natural selection? That is something we've seen in different populations of individuals over relatively short periods of time.
For example, the immune system went through some pretty rigorous natural selection in Europe through some of the plagues, such that the European descendants of survivors were far more resistant to certain bacteria (than, say, the natives of South America - which had disastrous consequences for said native americans when they first came into contact with Europeans).
You have to think carefully when discussing evolution, because the word is used in such a variety of ways, and everybody seems to have a different slant on it. For example, carmen writes "this increase in nutrient availability resulted in a decrease in jaw and tooth size", but a more accurate statement would be "this increase in nutrient availability reduced the selective pressure on individuals with smaller jaws and teeth, allowing the trait to become more prevalent in society".
It seems pedantic, I know (which is why even scientists will articulate it the way carmen did), but the initial statement often gives people the impression that we were actively changing (mutating), while in reality there was simply a shift in population phenotype from something that was not very common, to something that became more prevalent.
posted by kisch mokusch at 8:10 PM on April 15, 2007

Well there's the viral theory. It suggests that major leaps in evolution are caused by accidents created when genes get altered by virii. For example the leap from Neaderthal to Homo Erectus hasn't been fully explained.

Which reminds me of something I heard a couple of weeks ago in the Smithsomian museum of natural history..please read this with a southern drawl...Mother to seven year old son..."Now honey we believe that God created everything. In this museum they don't believe that."

At which point my head exploded.
posted by Gungho at 8:16 PM on April 15, 2007

Gungho, Homo Erectus preceded Neaderthal.
posted by carmen at 8:53 PM on April 15, 2007

Part of the problem is that the idea of "devolution" is nonsense. A bit of slime mold you step on is absolutely just as evolved as you or me, just evolved to fit a very different niche. If modern technology changes the environmental pressures we are subject to, that doesn't mean that evolution has stopped. It means that biologically, our niche has changed. If we become more dependent on our technology, that's evolution. If we become dumber (unlikely) that's evolution. (This is why Darwin himself never liked the term evolution.)

As already pointed out, however, humans are actually irreversibly tied into our overall system of technology; it no longer makes a lot of sense to separate the biological and the technological sides of our species. This is part of the idea behind Donna Haraway's cyborg feminism (warning: obtuse and rambling postmodern philosophy behind link; I couldn't get through it all myself). The idea being that we are all already cyborgs. Have been for some time now. (and for her purposes, that calls into question the validity of any argument from what is "natural", leading to liberation of women through the use of technology, but that's a completely tangential issue).

Humanity as the biological entities, humanity as the technological devices, and humanity as the memetic systems of ideas and beliefs are coevolving. They affect each other, and each of them are a part of us.

That's a good thing.
posted by Arturus at 10:44 PM on April 15, 2007

humans have and always will evolve so long as one group reproduces at a faster rate than other groups.

also, not all evolution is "forward" (see: idiocracy)
posted by nihlton at 1:52 AM on April 16, 2007

I invite anyone who thinks there's no evolutionary pressure any more to call up their favorite movie star and offer to impregnate or be impregnated by them.

In other words, sexual selection is still very much with us, and relative ease of movement around the world has arguably made it more efficient than it has ever been before.
posted by teleskiving at 4:02 AM on April 16, 2007

Survival of the fittest is retrospective. Fittest doesn't mean healthiest. An individual with a congenital illness may be fitter than an athlete with good physique, and selection continues unabated. A mistake made by eugenics and nazis etc is thinking that there is (or oculd be) a generically fitter human, whereas what is fitter in one environment is of no reproductive advantage, or a liability in another.

Also, watch the (recent release) movie "Idiocracy". It's a comedy about your question, set in the future of our society of today where we have effective birth control for any with the brains to use it properly, thus stupidity today is a trait with suchreproductive success that it shapes the gene pool of the people of the future. :-)
posted by -harlequin- at 9:26 AM on April 16, 2007

A lot of words on this page, but the answer only needed one sentence.

fvw: "You can't stop evolution, you can merely alter the natural selection criteria."
posted by Mr. Gunn at 9:28 AM on April 16, 2007